Keto Diet Theory Put to the Test
Michael Greger M.D. FACLM September 2nd, 2019 Volume 47
Do low-carb and ketogenic diets have a metabolic advantage for weight loss?
Video
Condensed transcript
When you don’t eat enough carbohydrates, you force your body to burn more fat. “However, this rise in fat burning is often misconstrued as a greater rate of net [fat mass] reduction [on the body].” But that ignores the fact that on a ketogenic diet your fat intake shoots up as well. The question is what happens to your overall body fat balance. You can’t empty a tub by widening the drain if you’re cranking up the faucet at the same time. Low-carb advocates had a theory, though: the so-called “carbohydrate–insulin model of obesity.”
Proponents of low-carb diets, whether a ketogenic diet or a more relaxed form of carbohydrate restriction, suggested that the decreased insulin secretion would lead to less fat storage. And so, even if you were eating more fat, less of it would stick to your frame. So, we’d be burning more and storing less, the perfect combination for fat loss—or so the theory went. To their credit, instead of just speculating about it, they decided to put it to the test.
Gary Taubes formed the Nutrition Science Initiative to sponsor research to validate the carbohydrate–insulin model. He’s the journalist who wrote the controversial 2002 New York Times Magazine piece, “What if It’s All Been a Big Fat Lie?”, which attempted to turn nutrition dogma on its head by arguing in favor of the Atkins diet, with its bunless bacon cheeseburgers based on the carbohydrate–insulin model. (Much of Nina Teicholz’s book The Big Fat Surprise is simply recycled from Taubes’s earlier work).
In response, some of the very researchers Taubes cited to support his thesis accused him of twisting their words. “The article was incredibly misleading,” one said. “I was horrified.” “He took this weird little idea and blew it up, and people believed him,” said another. “What a disaster.” It doesn’t matter what people say, though. All that matters is the science.
Taubes attracted $40 million in committed funding for his Nutrition Science Initiative to prove to the world you could lose more body fat on a ketogenic diet. They contracted noted NIH researcher Kevin Hall to perform the study. Seventeen overweight men were effectively locked in what’s called a metabolic ward for two months to allow researchers total control over their diets. For the first month, they were placed on a typical high-carbohydrate diet (50 percent carbohydrate; 35 percent fat; 15 percent protein), and then they were switched to a low-carb ketogenic diet (only 5 percent of calories from carbohydrate; 80 percent fat) for the second month. Both diets had the same number of daily calories. So, if a calorie is a calorie when it comes to weight loss, then there should be no difference in body fat loss on the regular diet versus the ketogenic diet. If Taubes was right, though, if fat calories were somehow less fattening, then body fat loss would become accelerated. What happened instead, in the very study funded by the Nutrition Science Initiative, was that “body fat loss slowed” upon switching to the ketogenic diet.
Wait…why do people think the keto diet works, if it’s actually slowing fat loss? Well, if you just looked at the readings on their bathroom scales, the ketogenic diet would seem like a smashing success. They went from losing less than a pound a week on the regular diet in the two weeks before they switched to losing three and a half pounds within seven days after the switch to the ketogenic diet. But what was happening inside their bodies told a totally different story. Their rate of body fat loss was slowed by more than half. So, most of what they were losing was just water weight. (The reason they started burning less fat on a ketogenic diet was presumed to be because without the preferred fuel, carbohydrates, their bodies started burning more of its own protein.)
And that’s exactly what happened. Switching to a ketogenic diet made them lose less fat mass and more fat-free mass; they lost more lean mass. That may help explain why the leg muscles of CrossFit trainees placed on a ketogenic diet may shrink as much as 8 percent. The vastus lateralis is your biggest quads muscle in your leg. Shrunk in thickness by 8 percent on a ketogenic diet.
Yes, the study subjects started burning more fat on the ketogenic diet, but they were also eating so much more fat on the ketogenic diet that they ended up retaining more fat in their body, despite the lower insulin levels. This is “diametrically opposite” to what the keto crowd predicted, and this from the guy they paid to support their theory. In science-speak, “the carbohydrate–insulin model failed experimental interrogation.”
In light of this “experimental falsification” of the low-carb theory, the Nutrition Science Initiative effectively collapsed…. but, based on their tax returns, not before Taubes and his co-founder personally pocketed millions of dollars in compensation.
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DOCTOR'S NOTE
This is the second in a seven-video series on keto diets. In case you missed the first one, check out
1) Is Keto an Effective Cancer-Fighting Diet?
3) Keto Diet Results for Weight Loss
4) Is Weight Loss on Ketosis Sustainable?
5) Are Keto Diets Safe? NO!
6) Keto Diets: Muscle Growth and Bone Density
RCT muscle building for 8 weeks builds 3 lbs of muscle on normal diet, but LOSE 3 ounce of muscle if on Keto diet
7) Does a Ketogenic Diet Help Diabetes or Make It Worse?
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